Field of the Invention
The present invention relates to an antenna device and a mobile wireless device provided with the antenna device and, more particularly, to an antenna device suitable for NFC (Near Field Communication) system and a mobile wireless device provided with the antenna device.
Description of Related Art
In recent years, an RFID (Radio Frequency Identification) system is implemented in a mobile wireless device such as a smartphone, and such a mobile wireless device is provided with an antenna device for performing near field communication with a reader/writer as a communication means. As an antenna device of such a type, an antenna device described in Japanese Patent No. 5,708,897 is known.
The antenna device described in Japanese Patent No. 5,708,897 has a configuration in which both ends of a radiation conductor are connected to a ground pattern to constitute a loop antenna.
However, in the antenna device described in Japanese Patent No. 5,708,897, only one loop antenna is constituted by the radiation conductor and ground pattern, so that a communication distance may become insufficient.
Further, in the antenna device described in Japanese Patent No. 5,708,897, the radiation conductor is provided on a plane position different from that of the ground pattern, so that the antenna device becomes disadvantageously large in planar size.